Apparatus for drying sludge



April 14, 1942-. G. c. UN GER, JR A APPARATUS I FOR DRYING SLUDGE Filed April 4, 1940 2 Sheets-Sheet l grwe/rvbo'v @Z/Jerf 6; ange April 14, 1942.

G. c. UNGER, JR 2,279,848

APPARATUS FOR. DRYING SLUDGE Filed April 4,1940 2 Sheets-Sheet 2 Patented Apr. 14, 1942 UNITED STATES PATENT OFFICE 2,279,848 APPARATUS FOR DRYING SLUDGE Gilbert 0. Unger, J12, Louisville, Ky., assignor to Engineering Development.-Gorporation, Jack sonville, Fla., a corporationv of Florida Application April 4, 1940,- SerialN i327,909

1 Claim.

This invention relates primarily to an apparatus for rapidly and economically drying sewage sludge, though it can be utilized to aid in the removal of moisture from, and the drying of other wet materials, to leavesubstantially dry solids.

Broadly stated, the invention contemplates the repeated mechanical turnover or disturbance of the sludge'or other wet materials in a shallow basin or tank, to thereby prevent the formation of a moisture retaining crust, and to continually bring fresh, wet material from the bottom to the surface, so that evaporation by sun and air can take place over a large area. It is also contemplated to associate fans or like air-propelling means with the apparatus, so that evaporation may be further speeded up when desired. It is a further object of the invention to so arrange the instrumentalities by which the foregoing results are achieved, as to easily adapt the mechanisms employed to either large or small installations, and to make it possible to easily add additional agitating units, while employing the same primary driving means.

Further objects and advantages of the invention will be set forth in the detailed description which follows. In the accompanying drawings:

Fig. 1 is a transverse vertical sectional view through one form of apparatus which I may employ in carrying out the invention.

Fig. 2 is a plan view of the structure of Fig. 1.

Fig. 3 is a vertical sectional View upon line 3-3 of Fig. 1.

Fig. 4 is a sectional View upon line 44 of Fig. 1.

Like numerals designate corresponding parts in all of the figures of the drawings. In the drawings, 5 designates a conventional relatively shallow, preferably concrete, sludge tank, into which the sludge left after bacterial sewage disposal processes may be delivered, either gravitally or by pumping. It is sometimes the case that water will collect in tanks of this sort, during periods of disuse, and I provide a valved pipe 6, by which water may be drawn oil when desired. Track rails I, disposed upon the walls of the tank, constitute supporting and guiding means for the track wheels 9 and I0. The wheels 9, are carried by a driven shaft H, to which rotation may be imparted through a chain drive I2, from electric motor Hi. This motor includes a conventional reduction gear, the casing of which is indicated at 14, so that the speed of rotation of the shaft I I may be made I relatively slow. The wheels I!) are mounted uporr'a'shaft l5,said shafts being free to rotate in "bearings lBand' I1. I

These'bearin'gs are secured to an, elongated carriage comprising stout channel or I beams l8 and |9.' These beams together with transversean'gles '20 and 2|, constitute a support for the motor l3, said motor being mounted upon a transverse'plate 22, whichispans the space between; and. rests upon, the beams I8 and I9.

Thus as themotor is'operated; the carriage,

motorand shafts will be caused-to travel bodily along the track rails I, or in other words, will be caused to move lengthwise of the tank 5.

It is well-known engineering practice to provide limit switches for electric motors used to reciprocate carriages of this sort, and it is contemplated to employ this well-known method of causing the carriage to travel back and forth along the tank.

I contemplate the use of one or more harrow or plow-like assemblies, as the means for continually bringing fresh layers of moist material to the surface of the sludge bed. In practice, the sludge will, at the beginning of the drying operation, be filled into the tank to a point slightly above the disc plows 24. These are merely conventionally shown in the accompanying drawings as being supported from shafts 25, that are carried by frames 26. Suitable hangers 21 support the frames 26 from the carriage.

Merely for purposes of explanation and illustration, I have chosen to show two of the plow or harrow units, each unit consisting of one of the frames 26, and its associated parts. However, the number of units employed will be determined by thev width of the tank 5. In some installations employing relatively narrow tanks, the harrow unit may be made wide enough so that only one unit need be employed. However, the use of separate units renders the matter of installation more flexible, in that additional units may be added as additional drying capacity is required, without disturbing the driving means for said units, to wit, the carriage. This can be accomplished by making the carriage long enough to take the maximum number of units ever to be used, but utilizing, in the beginning, less than the full number of plows capable of being moved by said carriage.

I preferably associate with each of the plow assemblies an electric motor-driven fan 28, the motors thereof being indicated at 29. These fans are preferably disposed in the hoods 30, and they function to direct strong blasts of air downwardly upon the material that is to be dried. It

a is to be understood that the showing of the-disc crust form over the surface of thesludge, which crust protects the underlying layers, but even in the absence of such crust, only the upper layers are contacted by the drying agencies. Consequently, the bringing to the surface of the 'wettest layers serves the two-fold purpose ofexposing these layers to the drying influences, and

of preventing the formation of the protective V crust. The use of open top, relatively'shallow tanks of considerable area facilitates the drying of large quantities of sludge or other waste material. Tanks of this nature permit, the ready entry; of the suns rays and air to. thematerialto be dried. However, while the most rapid drying through pipe 6, is gotten rid of at that point, and

to prevent the escape of solids through the pipe, I may dispose a screen 3| over the mouth thereof.

While I have shown the tank as having straight side walls, I may, if desired, mount the structure in an annular or circular tank, it being manifest that the shape of the tank is immaterial insofar as the broader aspects of the invention are concerned.

It is to be understood that the invention is not limited to the precise construction set forth, but

that it includes within itspurview whatever changes fairly come within either the terms or the spirit of the appended claim.

Having described my invention, what I claim I In combination, a tank adapted to receive can be had when the sun is shining,it isclear that some evaporative action will go on all the time, even on cloudy days. This is especially, true where fans such as those indicated at, 28 are provided to maintain a circulation of air.

. Any moisture, fluid enough to be drainedfoff sludge to be dried, an elongated carriage spanning said tank, means for guiding the carriage along the walls of the tank, power means for reciprocating the carriage alongthe tank, and a plurality of independent plowunit-s suspended from said carriage, each comprising a plurality of plow discs, said tank being .open at its top'to the free entry of air and air propelling means mounted upon the carriage above each of'the plow units acting to discharge air forcibly, upon .the surface of the material being upturned by'its associated plow GILBERT c. UNGER, JR. 

